Cache: Rewrite relocated paths in earlier

This changes the rewriting of the FC_FILE values for relocated caches to an earlier stage
while reading the cache. This is better, because it means all APIs will report the
rewritten paths, not just the once that use the list apis.

We do this by detecting the relocated case and duplicating the FcPattern and FcPatternElm
in an cache allocation (which will die with the cache) and then reusing the FcValueLists
from the cache.

This means that in the rewritten case we will use some more memory, but not the full
size of the cache. In a test here I had 800k of relocated caches, but ~200k of wasted
on duplicating the objects.

This should fix https://bugs.freedesktop.org/show_bug.cgi?id=106618

src/fccfg.c

@@ -324,11 +324,15 @@ FcConfigDestroy (FcConfig *config)
 
 FcBool
 FcConfigAddCache (FcConfig *config, FcCache *cache,
-		  FcSetName set, FcStrSet *dirSet)
+		  FcSetName set, FcStrSet *dirSet, FcChar8 *forDir)
 {
     FcFontSet	*fs;
     intptr_t	*dirs;
     int		i;
+    FcBool      relocated = FcFalse;
+
+    if (strcmp ((char *)FcCacheDir(cache), (char *)forDir) != 0)
+      relocated = FcTrue;
 
     /*
      * Add fonts
@@ -342,23 +346,43 @@ FcConfigAddCache (FcConfig *config, FcCache *cache,
 	{
 	    FcPattern	*font = FcFontSetFont (fs, i);
 	    FcChar8	*font_file;
+	    FcChar8	*relocated_font_file = NULL;
 
-	    /*
-	     * Check to see if font is banned by filename
-	     */
 	    if (FcPatternObjectGetString (font, FC_FILE_OBJECT,
-					  0, &font_file) == FcResultMatch &&
+					  0, &font_file) == FcResultMatch)
-		!FcConfigAcceptFilename (config, font_file))
 	    {
-		continue;
+		if (relocated)
+		  {
+		    FcChar8 *slash = FcStrLastSlash (font_file);
+		    relocated_font_file = FcStrBuildFilename (forDir, slash + 1, NULL);
+		    font_file = relocated_font_file;
+		  }
+
+		/*
+		 * Check to see if font is banned by filename
+		 */
+		if (!FcConfigAcceptFilename (config, font_file))
+		{
+		    free (relocated_font_file);
+		    continue;
+		}
 	    }
-		
+
 	    /*
 	     * Check to see if font is banned by pattern
 	     */
 	    if (!FcConfigAcceptFont (config, font))
+	    {
+		free (relocated_font_file);
 		continue;
-		
+	    }
+
+	    if (relocated_font_file)
+	    {
+	      font = FcPatternCacheRewriteFile (font, cache, relocated_font_file);
+	      free (relocated_font_file);
+	    }
+
 	    if (FcFontSetAdd (config->fonts[set], font))
 		nref++;
 	}
@@ -413,7 +437,7 @@ FcConfigAddDirList (FcConfig *config, FcSetName set, FcStrSet *dirSet)
 	cache = FcDirCacheRead (dir, FcFalse, config);
 	if (!cache)
 	    continue;
-	FcConfigAddCache (config, cache, set, dirSet);
+	FcConfigAddCache (config, cache, set, dirSet, dir);
 	FcDirCacheUnload (cache);
     }
     FcStrListDone (dirlist);

src/fcint.h

@@ -712,7 +712,7 @@ FcConfigModifiedTime (FcConfig *config);
 
 FcPrivate FcBool
 FcConfigAddCache (FcConfig *config, FcCache *cache,
-		  FcSetName set, FcStrSet *dirSet);
+		  FcSetName set, FcStrSet *dirSet, FcChar8 *forDir);
 
 FcPrivate FcRuleSet *
 FcRuleSetCreate (const FcChar8 *name);
@@ -1163,6 +1163,9 @@ FcPatternIterGetObjectId (const FcPattern *pat, FcPatternIter *iter);
 FcPrivate FcValueListPtr
 FcPatternIterGetValues (const FcPattern *pat, FcPatternIter *iter);
 
+FcPrivate FcPattern *
+FcPatternCacheRewriteFile (const FcPattern *pat, FcCache *cache, const FcChar8 *relocated_font_file);
+
 FcPrivate FcChar32
 FcStringHash (const FcChar8 *s);
 

src/fclist.c

@@ -448,41 +448,6 @@ FcListAppend (FcListHashTable	*table,
 	e = FcPatternObjectFindElt (font, FcObjectFromName (os->objects[o]));
 	if (e)
 	{
-	    if (FcRefIsConst (&font->ref) && !strcmp (os->objects[o], FC_FILE))
-	    {
-		FcChar8 *dir, *alias;
-		FcConfig *config = FcConfigGetCurrent (); /* FIXME: this may need to be exported as API? */
-
-		for (v = FcPatternEltValues (e); v->value.type != FcTypeString; v = FcValueListNext (v));
-		if (!v)
-		    goto bail2;
-		dir = FcStrDirname (FcValueString (&v->value));
-		if (FcHashTableFind (config->alias_table, dir, (void **) &alias))
-		{
-		    FcChar8 *base = FcStrBasename (FcValueString (&v->value));
-		    FcChar8 *s = FcStrBuildFilename (alias, base, NULL);
-		    FcValue vv;
-
-		    FcStrFree (alias);
-		    FcStrFree (base);
-		    vv.type = FcTypeString;
-		    vv.u.s = s;
-		    if (!FcPatternAdd (bucket->pattern,
-				       os->objects[o],
-				       FcValueCanonicalize (&vv),
-				       FcTrue))
-		    {
-			FcStrFree (s);
-			FcStrFree (dir);
-			goto bail2;
-		    }
-		    FcStrFree (s);
-		    FcStrFree (dir);
-		    goto bail3;
-		}
-		else
-		    FcStrFree (dir);
-	    }
 	    for (v = FcPatternEltValues(e), idx = 0; v;
 		 v = FcValueListNext(v), ++idx)
 	    {
@@ -491,7 +456,6 @@ FcListAppend (FcListHashTable	*table,
 				   FcValueCanonicalize(&v->value), defidx != idx))
 		    goto bail2;
 	    }
-	  bail3:;
 	}
     }
     *prev = bucket;

src/fcmatch.c

@@ -682,43 +682,9 @@ FcFontRenderPrepare (FcConfig	    *config,
 	}
 	else
 	{
-	    if (FcRefIsConst (&font->ref) && fe->object == FC_FILE_OBJECT)
-	    {
-		FcValueListPtr l = FcPatternEltValues (fe);
-		FcChar8 *dir, *alias;
-
-		while (l->value.type != FcTypeString)
-		    l = FcValueListNext (l);
-		if (!l)
-		    goto bail0;
-		dir = FcStrDirname (FcValueString (&l->value));
-		if (!config)
-		    config = FcConfigGetCurrent ();
-		if (config && FcHashTableFind (config->alias_table, dir, (void **) &alias))
-		{
-		    FcChar8 *base = FcStrBasename (FcValueString (&l->value));
-		    FcChar8 *s = FcStrBuildFilename (alias, base, NULL);
-		    FcValue v;
-
-		    FcStrFree (alias);
-		    FcStrFree (base);
-		    v.type = FcTypeString;
-		    v.u.s = s;
-		    FcPatternObjectAddWithBinding (new, fe->object,
-						   FcValueCanonicalize (&v),
-						   l->binding,
-						   FcTrue);
-		    FcStrFree (s);
-		    FcStrFree (dir);
-		    goto bail0;
-		}
-		else
-		    FcStrFree (dir);
-	    }
 	    FcPatternObjectListAdd (new, fe->object,
 				    FcValueListDuplicate (FcPatternEltValues (fe)),
 				    FcTrue);
-	  bail0:;
 	}
     }
     for (i = 0; i < pat->num; i++)

src/fcpat.c

@@ -373,6 +373,71 @@ FcValueListHash (FcValueListPtr l)
     return hash;
 }
 
+static void *
+FcPatternGetCacheObject (FcPattern *p)
+{
+  /* We use a value to find the cache, instead of the FcPattern object
+   * because the pattern itself may be a cache allocation if we rewrote the path,
+   * so the p may not be in the cached region. */
+  return FcPatternEltValues(&FcPatternElts (p)[0]);
+}
+
+FcPattern *
+FcPatternCacheRewriteFile (const FcPattern *p,
+                           FcCache *cache,
+                           const FcChar8 *relocated_font_file)
+{
+    FcPatternElt *elts = FcPatternElts (p);
+    size_t i,j;
+    FcChar8 *data;
+    FcPattern *new_p;
+    FcPatternElt *new_elts;
+    FcValueList *new_value_list;
+    size_t new_path_len = strlen ((char *)relocated_font_file);
+    FcChar8 *new_path;
+
+    /* Allocate space for the patter, the PatternElt headers and
+     * the FC_FILE FcValueList and path that will be freed with the
+     * cache */
+    data = FcCacheAllocate (cache,
+			    sizeof (FcPattern) +
+			    p->num * sizeof (FcPatternElt) +
+			    sizeof (FcValueList) +
+			    new_path_len + 1);
+
+    new_p = (FcPattern *)data;
+    data += sizeof (FcPattern);
+    new_elts = (FcPatternElt *)(data);
+    data += p->num * sizeof (FcPatternElt);
+    new_value_list = (FcValueList *)data;
+    data += sizeof (FcValueList);
+    new_path = data;
+
+    *new_p = *p;
+    new_p->elts_offset = FcPtrToOffset (new_p, new_elts);
+
+    /* Copy all but the FILE values from the cache */
+    for (i = 0, j = 0; i < p->num; i++)
+    {
+	FcPatternElt *elt = &elts[i];
+	new_elts[j].object = elt->object;
+	if (elt->object != FC_FILE_OBJECT)
+	    new_elts[j++].values = FcPatternEltValues(elt);
+	else
+	    new_elts[j++].values = new_value_list;
+    }
+
+    new_value_list->next = NULL;
+    new_value_list->value.type = FcTypeString;
+    new_value_list->value.u.s = new_path;
+    new_value_list->binding = FcValueBindingWeak;
+
+    /* Add rewritten path at the end */
+    strcpy ((char *)new_path, (char *)relocated_font_file);
+
+    return new_p;
+}
+
 void
 FcPatternDestroy (FcPattern *p)
 {
@@ -384,10 +449,10 @@ FcPatternDestroy (FcPattern *p)
 
     if (FcRefIsConst (&p->ref))
     {
-	FcCacheObjectDereference (p);
+	FcCacheObjectDereference (FcPatternGetCacheObject(p));
 	return;
     }
-	
+
     if (FcRefDec (&p->ref) != 1)
 	return;
 
@@ -1164,7 +1229,7 @@ FcPatternReference (FcPattern *p)
     if (!FcRefIsConst (&p->ref))
 	FcRefInc (&p->ref);
     else
-	FcCacheObjectReference (p);
+	FcCacheObjectReference (FcPatternGetCacheObject(p));
 }
 
 FcPattern *